Here goes my first post.
I have a stock ( so far ) 2003 mustang
gt When I first turn on my car I hear a deep clunk as if the car is checking the air bag, have heard it before on other cars so no biggie. But I keeps going it every few mins. Driving or idling. If I'm idling I notice my rpms drop a bit, hear the noise then the rpms go back to norm. Any ideas?